Capsinoids, which include capsiate, dihydrocapsiate, and nordihydrocapsiate, are molecules naturally present in chili peppers (Capsicum annuum L.). Capsiate is mainly found in a non-pungent cultivar of red pepper, CH19 Sweet, and is known to provide effects comparable to capsaicin, including activation of the capsaicin receptor. Capsinoids were first isolated in a unique variety of chili peppers, CH-19 Sweet, which does not contain capsaicin (Yazawa et al., 1989).
Capsinoids are capsaicinoid-like substances, which, as noted above, were first reported in the fruits of a non-pungent cultivar of pepper (Capsicum annuum L.), named CH-19 Sweet (Yazawa et al., 1989). Later, capsiate (4-hydroxy-3-methoxybenzyl (E)-8-methyl-6-nonenoate), dihydrocapsiate (4-hydroxy-3-methoxybenzyl 8-methylnonanoate), and nordihydrocapsiate (4-hydroxy-3-methoxybenzyl 7-methyloctanoate) were identified as the three major capsinoids in CH-19 Sweet (Kobata et al., 1998; Kobata et al., 1999). In capsinoids, the aromatic portion of capsaicinoids, vanillylamine, is replaced by vanillyl alcohol whereas their acyl residues are identical to those of corresponding capsaicinoids.
Previously capsaicinoids have been reported to promote energy metabolism, suppress body-fat accumulation and have the potential to provide a dietetic therapy for obesity and diabetes. However, capsaicin is strongly pungent and neurotoxic, which largely prohibits its administration to humans (Masuda et al., 2003). In contrast, capsiate can be taken in large amounts without pain and its effect on energy metabolism and weight loss mimic that of capsaicin (Masuda et al., 2003; Snitker et al., 2009). Today capsiate and CH-19 Sweet Pepper Extract are widely used as a dietary supplement to boost metabolism.
While capsinoids are structurally similar to capsaicin, the substance that causes pungency in hot peppers, capsinoids are significantly less pungent. Capsinoids are known to have an estimated “hot taste threshold” that is about 1/1000 that of capsaicin. Structural differences between capsaicin and members of the capsinoid family are shown in FIG. 1. Capsinoids have an ester bond in their structures as compared with the amide bond of capsaicin.
Capsaicin is believed to activate sensory receptors on the tongue that are used to detect thermal heat (Szallasi, et al. 1999). These receptors, Transient Receptor Potential Vanilloid 1 (TRPV1), are also present in the stomach and other organs (Nagy, et al. 2004). Activation of TRPV1 receptors is understood to trigger the sympathetic nervous system (SNS) (Iwai, et al., 2003). Capsaicin may mediate an increase in fat burning in humans and animals through activating the SNS.
Like capsaicin, capsinoids activate sensory receptors such as Transient Receptor Potential Vanilloid 1 (TRPV1) receptors (lida et al., 2003). Capsaicin and capsinoids may mediate an increase in fat burning in humans and animals through activating the SNS. However, unlike capsaicin, capsinoids do not initiate the heat sensation in the mouth, which may be because capsinoids cannot physically reach the TRPV1 receptors in the oral cavity due to structural differences compared to capsaicin. Nonetheless, capsinoids can activate TRPV1 receptors in the stomach, which has been shown to be important for the metabolic effects of both capsaicin and capsinoids (Ohnuki et al., 2001).
These metabolic effects are believed to contribute to the many health beneficial properties of both capsaicin and capsinoids, including anticancer, anti-inflammatory, and analgesic activities, as well as weight management (Macho et al., 2003; Sancho et al., 2002; He et al., 2009; Kawabata, et al. 2006; Handler, et al 2008). Studies have shown that both energy metabolism (Snitker et al., 2009; Inoue et al., 2007) and body temperature (Ohnuki et al., 2001; Hachiya, et al., 2007) elevations occur in humans following the administration of capsinoids or extracts of CH-19 Sweet. Moreover, body fat accumulation is suppressed following capsinoids intake (Ohnuki et al., 2001).
However, the contents of capsinoids in sweet peppers are extremely low. For example, only one pound of capsinoids can be extracted from 10,000 pounds of CH-19 Sweet peppers, which are expensive, drive the market price for capsiate, resulting in the price of capsiate extracted from sweet peppers to be extremely expensive e.g., US $600-25,000 for capsiate at 40% to 98% purity; alibaba.com/product-detail/High-quality-Capsiate-40-to-98_344832645.html?spm=a2700.7724838.35.1.J77Yht. Accordingly, more effective methods of producing capsinoids in a significant amount are desired.